The present invention relates to the transfer of food grade product in and out of a vessel. More particularly, the transfer is effected by means of vacuum generated in the vessel.
Food grade product is presently transferred from one vessel to another vessel by means of mechanical pumps that typically have rotating impellers or the like that effect the pumping of the food grade product. Food grade product may include for example eggs, liquid ingredients for the making of ice cream, raw or processed milk, liquid feed for livestock, liquid ingredients for the making of cheese, and the like. Reference herein is with respect to the transfer of raw milk from a holding tank at the production site to a vehicle tank for the transfer of the raw milk to a processing plant. The vehicle may be either a truck or a trailer, as depicted, that is transported by a tractor. Those skilled in the art will recognize that the same principles as are described herein are applicable to other transfers of food grade product from a first vessel to a second vessel. For example, the transfer of raw milk from the truck or trailer-mounted tank to a tank in the processing plant may be effected by the present invention. Additionally, the transfer of food grade product from a first vessel in the processing plant to a second vessel in the processing plant may be effected by the present invention.
Bulk milk pick-up from the point of origin as we know it today, consists of a truck or trailer-mounted stainless steel insulated transport tank. This transport tank is at atmospheric pressure and is therefore not operated at a vacuum and not operated at a pressure greater than atmospheric pressure. In order to effect the transfer of the raw milk form the holding tank to the transport tank, both the holding tank and the transport tank are vented to the atmosphere during the transfer operations.
The amount of time spent transferring the raw milk or other food grade product is a major cost item. With respect to the transport of raw milk, this time dictates the number of drivers and transport trucks needed to service a specified route of customers. The size of dairies has been ever increasing and the distance between dairies on a route is also increasing. Dairy herds of more than two hundred animals are not considered big any more. This increase in size has required that the size of the holding tanks at the dairy be greatly increased. In the past, a five hundred gallon holding tank was considered adequate. The holding tank now may hold several thousand gallons of raw milk. The sheer size of the holding tanks has greatly increased the transfer times. During the transfer of the milk from the holding tank to the transport tank both the driver and the truck are idle, greatly increasing the cost of transporting the milk from the dairy top the processing plant.
The milk is presently pumped from the holding tank at the farm (or other site of pick-up) to the transport tank by several different types of mechanical food grade impeller pumps. Presently, the pump that will pump the greatest volume of milk is a hydraulic driven stainless steel gear pump that will pump 230 gallons per minute. The cost of this unit is approximately $15,000.00 installed. To transfer two thousand gallons of milk product using this pump takes in excess of eight minutes.
The problem to the purchaser of the aforementioned pump, aside from the cost, is a problem that is years old. Every time milk is forced through pump impellers, the bacteria count in the milk is multiplied, and the molecular structure of the raw milk product is broken down. The more agitation that is caused by the pump, the greater the increase in the bacteria level and the greater the molecular breakdown that results in the milk. The increase in the bacteria level can pose a serious health concern. Additionally, the membrane around the fat molecule is broken by the pump agitation, resulting in undesired acidity in the milk. The molecular breakdown results in a decrease in the amount of the milk that can be used as an ingredient in dairy products, such as ice cream and cheese. The non useable portion is disposed of as the whey that is a by product of making the dairy products and is useful primarily for animal feed. The animal feed is sold at substantially reduced cost as compared to products for human consumption that could otherwise have been produced, thereby reducing the potential return from a quantity of raw milk.
An additional health concern is the cleanliness of the pump used for the transfer of the food grade product from vessel to vessel. Recently, an incident of salmonella infection being passed on to the ultimate consumer as a result of the lack of cleanliness of the transport vessel has been reported. It is a requirement that the transfer pumps be disassembled at least daily and sanitized to preclude such a problem from occurring. Sanitizing the impellers of the pump is a difficult task. Only a small amount of the salmonella organism left in the impeller can taint a subsequent load of food grade product that is pumped into the vessel.
With the increased size of dairy holding tanks comes the need to increase the volume load of the transport tanks that are mounted on a single truck chassis. Many states have stringent regulations governing the gross weight of vehicles using the public roads. With the increased transport tank volume and the weight of milk product that is being transported, there is a need to keep the transport tank weight to a minimum in order to maximize the milk volume that may be legally transported.
It would be a decided advantage in the food products industry to be able to more rapidly transfer food grade product from one vessel to another and at the same time minimize the mechanical agitation of the food grade product that results from such transfer to minimize the bacteria count increase in the food grade product and to minimize the molecular structure breakdown that also results form the mechanical agitation. Further, it would be an advantage to have a transfer system for food grade product that was more easily sanitized.
Using the vacuum system of the present invention for transferring raw milk, the milk flows at a rate in excess of 2,000 gallons per minute through a six inch diameter conduit while transferring milk from the holding tank and loading the transport tank, thereby reducing the loading time at the pick-up point by a factor of almost ten as compared to the fastest current means. This is accomplished using existing piping from the holding tank to the transport tank. Such piping is typically either two and a half inch pipe or three inch pipe. Coupled with the faster transfer time are a better load environment for the raw product, a significant lowering of the initial costs of the pumping system, and a reduction in clean-up and re-sanitizing time of the system as the raw product never touches any pumping mechanism, but is transferred solely through piping. No additional pump is necessary to effect the transfer of the food grade product. Additionally, from a health standpoint, there is no deleterious agitation of the food grade product heretofore associated with pumping by means of high speed impeller rotation. Further, the present invention includes a cleaning and sanitization system for cleaning and sanitizing both the tanks and the vacuum lines.
The present invention includes a cleaning apparatus for cleaning and sanitizing a tank, the tank for holding liquid food grade product, the liquid food grade product being transferred into and out of the tank by means of vacuum, the tank having a vacuum transfer system for transferring liquid food grade product includes apparatus for cyclically alternating a flow of cleaning fluid between the tank and the vacuum transfer system. The present invention is further, a method for cleaning and sanitizing a tank for holding liquid food grade product, the liquid food grade product being transferred into and out of the tank by means of vacuum, the tank having a vacuum transfer system for transferring liquid food grade product. The method includes the steps of:
(a) providing a cleaning fluid to a fluid inlet;
(b) cyclically alternating the flow of cleaning fluid between the tank and the vacuum transfer system; and
(c) venting the cleaning fluid from the tank and from vacuum transfer system;
whereby the tank and the vacuum transfer system are cleaned and sanitized during a single cleaning program having a selected series of rinse, cleaning and sanitizing cycles.